Perhaps the earliest completely rational system of politics was the one described in Plato's Republic. This work argues that the city should be a macrocosm of the soul, with reason serving to guide and govern it. Plato probably did not intend the hypothetical model of the city found in the Republic to serve as a template for a real government; his later work, Laws, is an example of what he thought would be a compromise between an ideal city and one that might actually work in practice. Nonetheless, as an intellectual construct, the city of the Republic has influenced many subsequent political theorists.

The key element of Plato's Republic is an educational system in which children are separated from their parents, and taught in a way that best suits their potential for future roles in the city; the recommended education is strictly rational, avoid such elements as art and poetry. Strikingly for his period, especially, Plato does not assign distinctive gender roles because he believed that masculine or feminine qualities of the soul can occur in physical bodies of either gender.

The Guardians, the wise, philosophically trained class who run the city, are selected by ability rather than popular vote, as Plato thought that democracy fails because it gives non-experts too much of a voice in decision making. Guardians as well as having rigorous training, are not permitted to own property at all, in order to prevent corruption. Their training emphasizes rational decision making.

In some ways, this sort of technocratic government seems like a good idea. It is rather dangerous when, for example, people who do not accept the solid scientific evidence for climate change or evolution are put in the position of being able to make decisions about funding for education or scientific research. On the other hand, concentrating power in the hands of a small class of people, as happens in such oligarchic societies as modern Russia, Saudi Arabia, and China, can lead to corruption and other forms of grave injustice and inequality. Thus even though the Republic is a fascinating thought experiment, as Plato himself realized, it probably is not a realistic model for a real government.